The present invention relates to the mounting structure of electronic devices and more particularly to an electronic device assembly promoting dense mounting of electronic devices and a method of connecting the devices.
To implement rapid processing and advanced functions, a semiconductor package with a plurality of functions, including memory and logic, arranged on a single semiconductor chip is attracting increasing attention. For example, Japanese Patent Laid-Open Publication Nos. 11-195746, 10-22449 and 5-13663 teach COC (Chip On Chip) structures. Japanese Patent Laid-Open Publication Nos. 7-297359 and 6-244360 disclose tridimensional mounting methods that connect semiconductor chips to circuit boards and then stack the circuit boards. Such conventional technologies, however, have the following problems (1) through (4) left unsolved.
(1) Arranging electronic devices having different functions on a single semiconductor chip results in an increase in chip size. This, in turn, increases the production cost for a chip and lowers the yield of a production line.
(2) The COC structures taught in the above-mentioned Laid-Open Publication Nos. 11-195746, 10-22449 and 5-13663 are not practicable without increasing the size of packages. Specifically, semiconductor chips separate from each other different in function each have a smaller area than a single semiconductor chip having various functions integrated thereon. The separate chips, however, increase the overall thickness and therefore the volume of a package when assembled together.
(3) It is necessary with the COC structure to cause underfill resin to flow into a gap between the active surfaces of semiconductor devices after the connection of the devices. The flow of the underfill resin into the above gap becomes more difficult as the pitch of bumps formed on a semiconductor device or the gap between two active surfaces decreases. As a result, irregular bubbles are left in the resin layer and structurally degrade long-range reliability. Further, the underfill resin sometimes reaches regions of the circuit surface of a semiconductor device where the resin would effect a device characteristic.
(4) The tridimensional mounting structures disclosed in Laid-Open Publication Nos. 7-297356 and 6-244360 each connect the individual semiconductor device to a preselected circuit board and then stack such circuit boards. Consequently, even semiconductor devices having small pad pitches or area bump arrays are connected to circuit boards before the stacking of circuit boards. As a result, the circuit boards have peripheral bump arrays. This increases the overall volume of the assembly, compared to an assembly in which circuit boards do not intervene between semiconductor devices.
It is therefore an object of the present invention to provide an electronic device assembly allowing two or more electronic devices to be connected together and allowing not only semiconductor devices and other active devices but also capacitors, resistors and other passive devices and a circuit board to be connected together, and a method of connecting the electronic devices.
It is another object of the present invention to provide an electronic device assembly allowing two or more electronic devices to be connected together without resorting to underfill resin, which would cause voids to remain therein after curing, and a method of connecting the electronic devices.
It is yet another object of the present invention to provide an electronic device assembly allowing a SAW (Surface Acoustic Wave) filter to be connected to another electronic device while being hermetically sealed at the same time and allowing another electronic device to be connected to the above electronic device by flip chip bonding, and a method of connecting the electronic devices.
It is a further object of the present invention to provide an electronic device assembly implementing tridimentional dense mounting without resorting to a carrier circuit board, and a method of connecting electronic devices constituting the assembly.
In accordance with the present invention, in an assembly in which a plurality of electronic devices of different kinds are connected to a single electronic device, the electronic devices are connected to each other by conductive portions implemented by metal, but insulated from each other by insulating portions implemented by an adhesive, sealable patterned resin layer.
Also, in accordance with the present invention, in a method of connecting at least two electronic devices included in an assembly in which a plurality of electronic devices of different kinds are connected to a single electronic device, the electronic devices are connected to each other by conductive portions implemented by metal, but insulated from each other by insulating portions implemented by an adhesive, sealable patterned resin layer. The method includes a step of subjecting the adhesive, sealable resin and electrodes to thermocompression at the same time.
Further, in accordance with the present invention, in a method of connecting at least two electronic devices included in an assembly in which a plurality of electronic devices of different kinds are connected to a single electronic device, the electronic devices are connected to each other by conductive portions implemented by metal, but insulated from each other by insulating portions implemented by an adhesive, sealable patterned resin layer. A first step connects the conductive portions by applying an ultrasonic wave while holding bumps and electrode pads aligned with the bumps in contact with each other. A second step connects a resin layer formed on any one of the electronic devices and a contact surface formed on a function element corresponding to the resin layer by thermocompression. The second step is executed after or simultaneously with the first step.
Moreover, in accordance with the present invention, in a method of constructing an assembly in which a plurality of electronic devices of different kinds are connected to a single electronic device, the electronic devices are connected to each other by conductive portions implemented by metal, but insulated from each other by insulating portions implemented by an adhesive, sealable and patterned resin layer. The method includes a step of connecting at least two electronic devices via thermosetting, sealable resin layer while maintaining, on a passive device mounted on any one of the electronic devices or on the circuit surface of the electronic device, a temperature of portions where resin constituting the resin layer would effect a device characteristic higher than a temperature of the other portions.